Declaring now would definitely end the debate over the hold that Trump has on the party and his future electability.
If he runs now and the GOP gets their clocked cleaned in the midterms because it's been shown that he was a drag on the party, then he's finished and will likely lose the primaries in 2024.
If he declares now and Republicans win, including many of those in tight races who he endorsed, then it's smooth sailing for Trump to 2024 and it's unlikely he'd face any serious primary challenge.
If he lays low until after the primaries, then what?
If he waits until after the primaries and we win back the house and senate, his momentum will trounce Biden or whoever they run against him, voter fraud or not.